Hydraulic lash adjuster

ABSTRACT

THIS DISCLOSURE RELATES TO A HYDRAULIC LASH ADJUSTER FOR OVERHEAD CAM ENGINES AND THE LIKE. OIL WITHIN THE THE PISTON BODY PASSES THROUGH THE TOP OF THE PISTON TO LUBRICATE A CLOSED SOCKET BETWEEN THE ROCKER ARM AND THE LASH ADJUSTER. A PIN, POSITIONED IN THE PASSAGE IS RECIPROCATABLE. THE EXTENT OF RECIPROCATION OF THE PINE WITHIN THE PASSAGE IN EITHER DIRECTION IS LIMITED TO PREVENT LOSING OF THE PIN PRIOR TO INSTALLATION OF THE LASH ADJUSTER INTO THE ENGINE.

United States Patent [56] References Cited UNITED STATES PATENTS [72]inventor MorrisVJhdd Mnsllegon, Mich.

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Attorney-Price, Heneveld, Huizenga and Cooper [54] HYDRAULIC ADJUSTERABSTRACT: This disclosure relates to a hydraulic lash ad- 5 Claims, 4Drawing Figs.

juster for overhead cam engines and the like. Oil within the,

123/9035, piston body passes through the top of the piston to lubricatea 123/9036, 123/9043, 184/6 closed socket between the rocker arm and thelash adjuster. A

[5i] Int. Cl. F0111: 9/10, pin, positioned in the passage isreciprocatable. The extent of FOll l/l8, FOll 1/24 reciprocation of thepin within the passage in either direction [50] Field of 123/90, islimited to prevent losing of the pin prior to installation of the 184/6(T) lash adjuster into the engine.

HYDRAULIC LASH ADJUSTER This application is a continuation-in-part ofSer. No. 741,750 filed July I, 1968, and now abandoned.

This invention relates to hydraulic lash adjusters, and moreparticularly to a novel hydraulic lash adjuster having an uniquelubricating means associated with the nose of its plunger.

In overhead cam shaft engines, the cams bear against rocker arms whichopen and close the engine valves. Each rocker arm assembly is pivoted ona lash adjuster which takes up slack in the valve train due to expansionof the parts as the engine heats up.

It has been proposed to lubricate the closed socket of the rocker arm inwhich the lash adjuster is seated from the interior of the plunger ofthe lash adjuster by employing a passage in the nose of the plunger anda pin within this passage. The conventional pin is merely inserted intothe passage from the outside of the nose and prevented from falling intothe center of the plunger by a flattened end portion which is largerthan the passage diameter. When positioned in the engine, the pin isprevented from falling out by the closed socket or seat of the rockerarm. However, the pin is subject to loss prior to assembly, that is,during assembly, shipment, and subsequent handling.

I have now discovered an improved hydraulic lash adjuster in which thepin in the lubricating passage has means to limit the reciprocal motionin each direction and the plunger is formed in two parts for insertionof the pin into the interior of the piston.

By various aspects of this invention one or more of the following, orother, objects can be obtained.

It is an object of this invention to provide an improved hydraulic lashadjuster for overhead cam shaft engines wherein the loss of parts priorto installation is avoided.

It is a further object of this invention to provide an improvedhydraulic lash adjuster in which a pin is provided in a lubricatingpassage between the adjuster and a rocker arm wherein the extent ofreciprocation of the pin in the passage in each direction is limited.

, It is a still further object of this invention to provide a closedsocket rocker arm assembly having a hydraulic lash adjuster with animproved lubricating means for the closed socket connection with thehydraulic lash adjuster.

Other aspects, objects, and the several advantages of this invention areapparent to one skilled in the art from a study of this disclosure, thedrawings, and the appended claims.

According to the invention, a hydraulic lash adjuster for an internalcombustion engine with a closed socket rocker arm has a body, a plungerreciprocatable within the body, the plunger having a central cavity witha check valve means in the lower portion thereof, and lubricating oilinlet means through the body communicating with the interior of theplunger. Socket support means is provided in the upper outer portion ofthe plunger. A lubricating passage extends from the interior of theplunger to the socket support means and a pin is positioned within thepassage. The pin is reciprocatable within the passage but is limited inthe extent of reciprocation in each direction.

To this end, the plunger is provided with a two-piece body, the socketsupport means preferably being press fit into the top portion of theplunger. In this manner, the reciprocatable pin can be inserted into thepassage prior to assembly of the pin into the lubricating passage.

The invention will now be described with reference to the accompanyingdrawings in which:

FIG. 1 is a schematic representation of an overhead cam, valve trainhaving a tappet according to the invention;

FIG. 2 is an enlarged sectional view of ihe tappet shown in FIG. 1;

FIG. 3 is an enlarged sectional view of the upper portion of a tappetshowing a second embodiment of the invention; and

FIG. 4 is a view of a tappet similar to FIG. 3 showing a thirdembodiment of the invention.

Referring now to FIGS. 1 and 2, a valve 2 having a spring 4 and retainer6, is actuated by rocker arm 8 through a cam shaft I0 and cam 12. Therocker arm 8 pivots about a solid or closed socket 14 on tappet 16. Thetappet, which automatically adjusts for lash, contains a body 18 with aplunger 20. The plunger 20 is biased in the upward position against theclosed socket 14 of rocker arm 8 through a spring 26. The plunger 20 hasan internal cavity 28 which opens into a bottom'compression chamberthrough check valve plate 22. A spring 24 biases valve plate 22 againstthe bottom of plunger 20. A valve retainer 25, which holds the checkvalve assembly in place, is held against the bottom of plunger 28 byspring 26.

Lubricating oil enters cavity 28 through port 32 and port 30. As isconventional in hydraulic valve assemblies, the oil passes throughcavity 28 through the bottom portion of the plunger 20 into the bottomcompression chamber.

The'reciprocal motion of the plunger 20 is limited at the lowerextremity by shoulder 33 and at the upper extremity by split ringretainer 50 positioned in annular groove 48. The split ring 50 can be ofconventional design or can be a ring according to the inventiondescribed and claimed in US. Pat. No. 3,358,660.

It is desirable to lubricate the closed socket 14 as it rotates on theupper spherical head or nose 34. To this end, a circular bore 49 and areciprocable pin 44 are provided. The pin 44 is adapted to reciprocatewithin bore 49 and has a shoulder 46 to limit the extent of upwardmovement of the pin 44 relative to spherical head 34. The extent ofdownward movement of pin 44 relative to head 34 is limited by plate 42which is seated on shoulder 38. Plate 42 is perforated to permit oil topass into bore 40 from cavity 28. The holes are positionedcircumferentially of the pin 44 to permit the oil to pass freely throughplate 42.

The pin can be easily assembled into the head 34 by providing a pressfit at 36 between the spherical head 34 and the inner annular upperportion of plunger 20. Thus, the tappet can be easily assembled bypositioning pin 44 within spherical head 34, positioning plate 42 onshoulder 38 and forcing spherical head 34 into plunger 20.

The apertured plate 42 permits the oil to flow therethrough into theinner chamber in spherical head 34. The flow of oil through bore 40 islimited by the closed socket 14. Due to the tolerances between pin 44and circular bore 40, the oil is permitted to slowly pass through bore40. The pin 44 does not restrict the flow of oil through bore 40 duringnormal engine operation. Due to engine vibration and normal movement ofthe automobile, the pin 44 will ten to vibrate and reciprocate in bore40. This reciprocal movement of pin 44 in bore 40 keeps the bore fromclogging with dirt so that the lubricating oil can continuously passthrough the bore and provide a thin film of lubrication for closedsocket M.

In FIG. 3, like numerals have been used to describe like parts. Thespherical head 34 is slightly shorter at 60 to provide a gap betweenshoulder 38 and the bottom of head 34. A lubricating pin 52 has an uppercircular portion 54 which is slidabie in bore 40 tothe same extent thatthe upper portion of pin 44 is slidable in bore 44). The lubricating pincontains an expanded central portion 56 which extends downward andoutward to form an annular ring 58. The annular ring fits into thecavity between 60 and shoulder 38 to limit both the upward and downwardmovement of pin 52 relative to spherical head 34. Thus, in thisembodiment, the lubricating pin 52 functions to permit oil to pass intothe central chamber in spherical head 34 and through bore 40 tolubricate socket 14 while preventing the bore 40 from being plugged.

In FIG. 4, like numerals have been used to designate like parts. In thisembodiment, the lubricating pin 62 has a flattened head 64 which seatsagainst a recessed shoulder 66 in spherical head 36. The lubricating pinhas an annular central portion and is reciprocatable within. bore st) tothe same extent as are upper portions 54 of lubricating pin 52 and theupper portion of pin in bore 50. An oval lower portion 70 of lubricatingpin 62 restricts the upward movement of lubricating pin 62 withinspherical head 34. Thus, in this em-,

bodiment, the lubricating pin 62 is reciprocatable within bore 40 tokeep thesame clean and also permits oil to flow through bore 40 tolubricate the socket 14. in this embodiment, the oval can be formed intwo ways. One is by simply pinching down the central portion of pin 62after it has been inserted into spherical head 34. Another is to pinchthe central portion only to the extent that it can be forced throughopening 40, the pinched portion 70 having sufficient resilience andmemory to return to its pinched oval shape. in each case, the oval lowerportion 70 prevents the lubricating pin from falling out of thespherical head 34. In the first way of forming the portion 70, thespherical head can be press fitted to the upper portion of plunger afterforming portion 70. in the second way, the spherical head 34 can be anintegral part of the plunger 20.

Thus by the invention, the lubricating pin performs the function ofkeeping the lubricating bore open and is retained in the spherical headbefore the tappet is assembled in the valve train.

Reasonable variation and modification are possible within the scope ofthe foregoing disclosure, the drawings, and the appended claims of theinvention without departing from the spirit thereof.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows.

I claim:

1. In an internal combustion engine having a rocker arm forming a closedsocket, a hydraulic lash adjuster supporting said socket, the lashadjuster having a body, a plunger reciprocable within said body, saidplunger having a central cavity and an open end; a lubricating oil inletmeans communicating with said central cavity of said plunger; a closureelement in said open end of said plunger forming a pivot with saidclosed socket for said rocker arm, the bottom of said closure elementextending downwardly into the upper end of said plunger; lubricatingmeans extending from said cavity of said plunger through said closureelement for lubricating said pivot; the improvement which comprises:said lubricating means comprising a passage through said closure elementbetween the interior of said plunger and the outer surface of saidclosure element; a pin in said passage with the upper portion thereofwithin said passage and freely reciprocable therein, said pin having anenlarged intermediate portion larger than said passage to limit theextent of upward motion of said pin in said passage; and an aperturedplate seated on said annular shoulder beneath said pin to limit thedownward motion of said pin with respect to said passage but to permitoil to freely flow therethrough whereby said closed socket is lubricatedwith a thin film of oil.

2. An internal combustion engine according to claim 1 wherein saidclosure element comprises a spherical head having a downwardly extendingbody which is press fit into said plunger body.

3. An internal combustion engine according to claim 2 wherein the lowerportion of said closure element is positioned against said aperturedplate holding said plate against said shoulder.

4. In a hydraulic lash adjuster for an internal combustion engine, saidlash adjuster having a body, a plunger reciprocable within said body,said plunger having a central cavity and an open upper end; an annularshoulder formed at the upper end of said central cavity; a lubricatingoil inlet means communicating with said central cavity of said plunger;a closure element in said open end of said plunger forming a pivot for alubricating arm, the bottom of said closure element extending downwardlyinto the open end of said plunger to a point above said inner annularshoulder, leaving an annular space between the lower end of said closureelement and said annular shoulder; lubricating means extending from saidcavity of said plunger through said closure element for lubricating saidpivot; the improvement which comprises: said lubricating meanscomprising a passa e through said closure element between the interiorof sai plunger and the outer surface of said closure element; a pin insaid passage with the upper portion thereof within said passage andfreely reciprocable therein, said pin having an annular flange at thelower portion thereof, said flange being positioned within said annularspace such that the extent of reciprocation of said pin in said passageis limited by the lower end of said closure element and said shoulder.

5. In a hydraulic lash adjuster for an internal combustion engine, thelash adjuster having a body, a plunger reciprocable within said body,said plunger having a central cavity; a lubricating oil inlet meanscommunicating with said central cavity of said plunger; a spherical headforming the upper outer portion of said plunger providing a pivot for arocker arm; lubricating means extending from said cavity of said plungerthrough said closure element for lubricating said pivot; the improvementwhich comprises: said lubricating means comprising a passage throughsaid spherical head between the interior of said plunger and the outersurface of said spherical head; a pin in said passage formed from ahollow tubular member having a closed upper end flattened to a diameterlarger than said passage to limit the downward movement of said pin insaid passage; and a lower portion of said pin beneath said passage beingpinched to an oval shape to thereby limit the extent of axial movementof said pin in said passage.

